Common brain diseases, such as brain tumors, Parkinson's disease, and epilepsy, not only adversely affect the patients' quality of life but sometimes can also directly contribute to the patients' death. Invasive surgical procedures are usually performed after conservative treatments, such as medication or physical therapy that fails to relieve the patients' symptoms.
Generally, a surgeon may plan a surgical pathway to reach a targeted surgical site based on certain pre-operative data. However, the planned pathway may need to be altered due to changed conditions that occur after the collection of the pre-operative data. Some example of the changed conditions include a change of the patient's position on the operating table, a change in the patient's physiological condition, or the insertion of the surgical instrument itself. Any deviation from the pre-operative planned pathway often leads to further complications or an increased mortality rate.